Sealed system with reverse cycle defrosting



Aug. 16, 1955 c M|LLMAN 2,715,318

SEALED SYSTEM WITH REVERSE CYCLE DEFROSTING Filed April 5, 1950 5Sheets-Sheet l I :5: /6- IE-I 7 IN V EN TOR. 76 C 712 077 z'// 71a71.

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Aug. 16, 1955 c. MILLMAN SEALED SYSTEM WITH REVERSE CYCLE DEFROSTING 5Sheets-Sheet 2 Filed April 5, 1950 V 33 MQQ INVENTOR. 6/27720/7 /yZ//77Y477.

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SEALED SYSTEM WITH REVERSE CYCLE DEFROSTING Filed April 5, 1950 3Sheets-Sheet 3 THE/7,7957

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United States Patent lull SEALED SYSTEM WITH REVERSE CYCLE DEFROSTINGClinton Millman, Greenville, Mich.

Application April 5, 1950, Serial No. 154,110

16 Claims. (Cl. 624) This invention relates generally to the method ofand apparatus for the control of refrigeration apparatus and isparticularly adapted among other uses for defrosting domesticrefrigerators.

Reversed cycle defrosting has been used in prior art refrigeratingsystems but, due to the complexity of the valving arrangement, has beenlimited exclusively to systems of the commercial type and has not beenapplied to the so-called household or domestic refrigerators. Defrostingin the household refrigeration art has been limited to the shutting downof the refrigerating unit and permitting the low side thereof togradually warm up permitting the accumulated frost to melt and drip fromthe evaporator unit. With the appearance of the domestic refrigerator inwhich comestibles are stored in two zones, one in a freezing zone inwhich the comestibles are maintained in a frozen condition below 32 F.and another section in which comestibles are maintained in a nonfreezingcondition, the limitations of this type of defrosting were such that itis no longer practical since the food stuffs stored at the lower orfreezing temperature would melt and such defrosting could only becarried with the frozen comestibles storage compartment empty. I amaware that various efforts have been made to adapt the reverse cycle ofdefrosting to such household units but such an arrangement has not metwith success.

It is therefore a primary object of this invention to provide a newdefrosting arrangement for household refrigerators for quicklydefrosting the evaporator unit without a corresponding rise intemperature of the comestibles refrigerated thereby.

Another object of this invention is to provide such a system in whichfor short periods of time the normal evaporator serves as a condenserandthe normal condenser serves as an evaporator for reverse cycledefrosting in which heat is applied at the proper point for defrostingthe evaporator without appreciably raising the temperature of the storedcomestibles.

Another object of this invention is to provide such I a reverse cycledefrosting system which is particularly adapted for use on the usualcapillary tube type her'meti cally sealed domestic refrigeration system.

2,715,318 Patented Aug. 16, 1955 ice Another object of this invention isto provide a defrosting cycle in which the pressures in the system aresubstantially balanced before the reverse cycle operation is started sothat the valve may be positively operated with a minimum amount offorce.

Another object is to provide such a system in which the defrosting cycleis initiated by a de-energized time period of the motor compressor unitof predetermined length, a predetermined length of reverse cycleoperation following by a predetermined length of de-energized conditionof the motor compressor unit prior to its being restored to normaloperation.

Another specific object of this invention is to provide such adefrosting system in which the reverse cycle operation of therefrigerating system is accomplished independently of any action of thenormal control for the refrigerating system.

Another object is to provide a hermetically sealed valve unit of minimumsize which is particularly adapted for use with domestic refrigeratedsystems.

Other objects of the invention will be apparent from the specification,the appended claims and the drawings 1 in which drawings:

i r and the electrical control system;

Fig. 3 is a view in central vertical cross section of the valve shown inFig. 2 within the hermetically sealed motor compressor unit;

Fig. 4 is a view showing a modified form of the invention in which thehermetically sealed valve unit is located externally of the motorcompressor unit;

Fig. 5 is a view showing a modified form of electrical control system;

Fig. 6 is a view partially in central vertical section of a modifiedform of the valve unit and including the actuator therefor; and

Fig. 7 is a view showing certain details of the mechanism forcontrolling the reverse cycle operation.

Referring to the drawings by characters of reference, the numeral 1indicates generally a household type of refrigerator having a cabinet 2with an access door 4 and containing a compartment 6 adapted to bemaintained at temperatures above freezing, an evaporator 8, the interiorof which provides a frozen storage compartment 10 which may, forexample, be maintained at about 0 Another object of this invention is toaccomplish a rearrangement of the refrigerating system elements forreverse cycle refrigeration by means of a valve located within thesealed refrigeration system.

Another object of this invention is to provide an imroved valve arranement which is of minimum size and which will require a minimumoperating force.

Another object of this invention is to provide a new control system forcontrolling defrosting by a reverse cycle operation.

A more specific object of this invention is to provide F. The cabinet 1further includes a high side containing compartment 12 in which islocated a hermetically sealed motor compressor unit 14, a condenser 16and a control mechanism 18. The unit 14, condenser 16, and evaporator 8are connected together into a sealed system.

As will be seen in Fig. 2 the motor compressor unit 14 includes a motor20 which may be of the usual low starting torque split phase typedriving a pump or compressor 22. The motor 20 contains the usualstarting and running windings (not shown in Fig. 1 but shown as S and Rin Fig. 5) which are energized from a suitable source of electricalenergy such as lines L1, L2. Line L1 is connected through a suitableoverload device 24 and line 25 to the common connection between thestarting and running windings. The other terminal of the running windingis connected through conductor 26 and switch SW1 of the controlmechanism 18 to one end of the coil 28 of the starting relay 30. Theother end of the coil 28 is connected through a conductor 32 and controlswitch 34 to the line L2. The other terminal of the starting winding isconnected by conductor 36 through the switch contacts a of the relay 30to the conductor 32.

Upon closure of the switch 34 due to a rise in temperature of theevaporator 8 the starting and runing windings of the motor 20 will beenergized for starting the motor 20. As is normal, the heavy startingcurrent drawn by he run i W ud ng' ew hg through the rel y ,whld n 8 9the s a t n re y w l cl e t e contacts a of he elay .3!) wh reby he motr st r i g winding is e gi ed and he met r wi ar e the mot r has icreased in speed sufficiently so that it will operate on single phase cure fl w n th ough h runn ng windi g, he curr throu h t e e ay d ng 8 lha pp ffieieut t Pe i he ta s a of the relay 30 t p here t e-e e iz hstar i g ind ng. The motor l eutinu ope t from he n g w din i theu ue th eh- The evaporator 8 is ppl ed w th liqu d refrigeran remt eeudeh erl6 threu h a suitable feed evice such s t e e l ry tube 38 ischa in in equ d e ing header!!!) of the'evaporator 8. This tube 38 acts duru he etim o nen un in een e o h m tor compressor unit 14 to equalize thepressures in the sysern.- he nde se lfi is n n on ec e by means fconduit 42 through the valve device 44, to be more fully describedbelow, through theconduit 48 to the discharge ert f the m r s o 2 he n ae por of he c muresser .2 is e n t reugh c du t 46 and the valve 44,located within the interior 50of the housing 52'which encloses the motor20 and compressor 22, to the interior 50 which in turn is connected bymeans of a suction conduit 54 with the discharge header 56 of the evapeate During normal operation of the refrigerating system vaporousrefrigerant will be drawn from the header 56 of the evaporator 8 throughthe conduit 54, the interior 50 of the housing 52, the valve device 44,conduit 46 into the compressor 22 wherein the refrigerant is raised inpressure and discharged through the conduit 48, valve device 44, conduit42 into the condenser 16 wherein its heat is radiated and the vapor iscondensed to a liquid which then flows through the capillary tube 38 tothe inlet header 40 of the evaporator 8. Liquid flowing into the header40 flows around through the evaporator absorbing heat which causes it tovaporize which vaporous refrigerant finds its way to the dischargeheader 56 for subsequent recirculation,

v The control mechanism 18 includes a selfstarting synchronous motor 60(Fig. 7) which may be of the electric clock type Which drives a switchactuating or cam disk 62 through a suitable gear reduction 64. The disk62 in turn controls the opening and closing of switches SW1, SW2 andSW3. In the form of the invention shown in Fig. 2 only two switches SW1and SW2 are used and therefore, for purposes of simplicity, the thirdswitch SW3 shown in Fig. 7 is omitted from the showing of the mechanism18 in Fig. 2. The switch SW1 is located in series in the conductor 26and as shown in Fig. 2 is located intermediate the relay 30 and therunning winding of the motor 20. Normally switch SW1 is held closedsince during substantially the entire rotation of the disk 62, the diskfollower 66 thereof rides on the normal diameter circular peripheralsurface 68 of the disk 62. Therefore, during normal operation of therefrigeration system, the switch SW1 is maintained closed wherebycontrol of the starting and stoppingof the motor ;20 is effected bymeans of the control switch '34.

The valve device 44, to be described in greater detail below, isshiftable by means of the solenoid actuator 70 to a position in whichthe refrigerant will be directed as described above and to a secondposition in which the conduit46 is connected to the conduit 42 wherebythe compressor will withdraw vaporous refrigerant from the condenser 16and discharge it through the conduit 48 and the valve device 44 into theinterior 50 of the housing 52 from whence it flows outwardly through theconduit' 54 to the evaporator 8. The high pressure refrigerant flows ino he vapora o 8 wher by it heat of e d nsa tion heats the evaporator andthe resulting condensed liquid refrigerant flows through the capillarytube 38 back to the condenser 16 wherein it is vaporized due toabsorption of heat therefrom. The vapor then flows through the conduit42 back to the compressor 22 for recirculation in the refrigeratingsystem substantially as just described.

One terminal of the energizing winding of the solenoid actuator 70 isconnected by means of conductor 72 through device 24 to the line L1. Theother terminal of the winding of this actuator 70 is connected by meansof conductor 74 to one terminal of the switch SW2. The other terminal ofthis switch SW2 is connected to the conductor 26 intermediate the switchSW1 and the winding 28 of the relay 39. The motor (Fig. 7) is providedwith terminals 76 and 78. The terminal 76 is connected by means ofconductor 80 to the portion of the conductor 26 connected in common tothe switches SW1 and SW2. The terminal 78 is connected by means ofconductor 82 to the line 25 so that opening of the .overload device 24will stop the motor 60. It will be seen that the motor, 60 is energizedfrom the lines L1 and L2 upon closure of the control switch 34 through acircuit whichextends from the line L1 through theconductors 25 and 82,the clock motor 60, conductor 80, portion of the conductor 26, relaywinding 28, conductor 32, switch 34 back to the line L2 and the clockwill act to measure running time of the compressor. Once each revolutionof the disk 62, the disk follower 66 will drop down into the depressionor recess 84 and. permit the switch SW1 to open. Opening of the switchSW1 de-energizes the motor 20 permitting pressures within therefrigerant system to equalize through the constantly open capillarytube 38.

After continued predetermined rotation of the disk 62, the disk follower86 of the switch SW2 willhave been pushed upwardly by the abutment orenlargement 88 of the disk 62 to close the switch SW2. It should berecalled that during this time the switch 34'is in closed positioncalling for the motor compressor unit 14 to remove heat from theevaporator 8. Closure of the switch SW2 acts to energize the solenoidactuator 70 through a circuit which extends from line L1 through theoverload device 24, conductor 72, actuator 70, conductor 74, switch SW2,conductor 26, winding 28, conductor 32, switch 34 to line L1.Energization of the actuator 70 shifts the valve device 44 into aposition in which the condenser 16 acts as an evaporator and theevaporator 8 acts as a condenser. Shortly thereafter the disk'follower66 of the switch SW1 will ride up the side of the depression 84 to closethe switch SW1. Closure of switch SW1 energizes the normal circuit ofthe motor 20 whereby themotor 20 operates to drive the compressor 22 forwithdrawing refrigerant from the condenser 16 and discharging it intothe evaporator 8. Heat is thus removed from the condenser 16 anddeposited in the evaporator 8 which quickly raises the temperature ofthe evaporator 8 and permits the frost accumulated thereon during therefrigerating cycle of the evaporator 8 to melt and disengage itselffrom the evaporator. After a predetermined reverse cycle operation ofthe motor compressor unit14, the disk 62 will have rotated sufficientlyto permit the disk follower 66 to drop into the depression 90 of thedisk 62 opening the switch sw1 and de-energizing the motor 20 againpermitting the pressures in the refrigerant system to equalize.Subsequently the disk follower 86 of the switch SW2 will have passedbeyond the abutment 88 so that the switch SW2 will open to de-energizethe actuator 70. As the pressure within the valve device 44 and therefrigerating system will already have or is about equalized, the valvedevice 44 will shift, in a manner to be described below, back to itsnormal position in which it directs the discharge of refrigerant fromthe compressor 22 into the condenser 16 and from, the evaporator 8 tothe compressor 22. After sufiicient time has been allowed for thisoperation, the 'disk 62 will have been rotated so that the disk follower66 will then be 5 riding on the normal diameter portion 68 whereby theswitch SW1 is again closed. Closure of the switch SW1 transfers controlof the motor compressor unit 14 to the normal control switch 34. Theswitch 34 being closed, the motor is again energized for operation ofthe compressor 22 as described above and refrigerant is then withdrawnfrom the evaporator 8, discharged into the condenser 16 where it isliquified and flows through the capillary tube 38 into the evaporatorfor recycling whereby the heat is removed from the evaporator anddischarged from the condenser. The disk follower 86 is so arrangedrelative to the disk 62 that the switch SW2 will be closed only duringthe time that it is riding on the abutment 88. The disk follower 86 mayor may not ride down into the depressions 84 and 90 but this isimmaterial since the switch SW2 will remain open at all times exceptwhen it is riding on the abutment 88.

The form of control circuit shown in Fig. 5 is quite similar to thatshown in Fig. 2 with certain exceptions described below. in this formthe clock is arranged to be continually driven (except during periodswhen device 24 is open) and acts to place the refrigerating system indefrost or reverse cycle operation at fixed predetermined time periodsirrespective of the operating time of the motor compressor unit 14. Toaccomplish this the terminals 76 and 78 of the clock are connected bymeans of conductors 92 and 94 respectively to the line L1 and conductor25. The switch SW3 which operates concurrently with the switch SW2 asshown in Fig. 7 is provided to insure continued operation of the motor20 during defrosting independently of the switch 34. As shown in Fig. 5the switch SW1 is located in the conductor 32 between the relay 30 andthe control switch 34 instead of in the conductor 26 as shown in Fig. 2.One of the contacts of each of the switches SW1, SW2 and SW3 isconnected together and is connected by means of conductor 32 through thecontrol switch 34 to the line L2. During normal refrigerating operationof the system, the switches SW2 and SW3 will be open and the switch SW1will be closed as described in connection with Fig. 2. T he operation ofthe motor 20 therefore will be under control of the switch 34. Duringreverse cycle defrosting however the switches SW2 and SW3 will also beclosed as well as switch SW1 as indicated above. The switch SW3 acts toclose a circuit between the conductors 32 and 92 whereby switch SW3connects the common terminals of the switches SW1, SW2

and SW3 to the line L2 through the conductor 92 in bypass arrangementaround the switch 34 so that defrosting in reverse cycle operation maybe carried on independently of the operative condition of the switch 34.

In Fig. 3, the valve device 44 is shown in greater detail. The device 44includes an elongated casing 109 having a central passageway or port 102which extends longitudinally through the casing and opens outwardlythrough the opposite end walls 104 ad 106. Substantially midway betweenthe walls 104 and 106 the casing 100 is provided with an outwardlyextending flow passageway 108 to which the conductor 42 may beconnected. The casing 100 is provided with two pairs of oppositelyfacing valve ports 110, 112, 114 and 116 defined by valve seats 118,120, 122 and 124 respectively. The valve seats are preferably all ofequal diameter and are relatively thin in cross sectional area.

A cylindrical valve operating stem 126 extends completely through thepassageway 102 and has a central enlarged diameter portion 128 andadjacent intermediate diameter portions 130, 132 at either end of theenlarged diameter portion. These portions 130 and 132 may be externallythreaded. Shoulders 134 and 136 are formed at the intersections of theintermediate diameter portions with the enlarged diameter portion 128.Ends 138 and 140 of the operating stern 126 outwardly of theintermediate diameter portions 130 and 132 respectively are of reduceddiameter and form shoulders 142 and 144 at their intersections with theintermediate diameter portions 130 and 132.

Valve seat members 146 and 148 are carried on the intermediate diameterportions 130 and 132 of the operating stem 126 and have seat engagingdisks 150 and 152 which engage against the shoulders 134 and 136respectively. The disks 150 and 152 are of larger diameter than theenlarged diameter portion 128 and en gage alternately with the valveseats 118 and 122. The valve seat members 146 and 148 are each providedwith a rigid intermediate member 154 and 156 which screwthreadedlyengage the external threads of the intermediate diameter portions 130and 132 to hold the disks 150 and 152 against the shoulders 134 and 136.The valve members 146 and 148 are further provided with a second set ofdisks 158 and 160 which are in face-to-face relation with the backingmembers 154 and 156 on the opposite side from the disks 150 and 152 andwhich may be cemented thereto if desired. The disks 158 and 160 engagerespectively with the valve seats 120 and 124.

The opposite ends of the passageway 102 are of enlarged diameter andinternally threaded for reception of externally threaded plug or endmembers 162 and 164. The inner surface of the plug member 162 definesthe seat 120 which surrounds the port 112. The plug 162 is provided witha plurality of outwardly extending passageways 166 which open inwardlyinto the port 112 and outwardly of the valve device 44 and is providedwith a bore 168 aligned concentrically with the passageway 102. A hollowcylindrical sleeve 170 which slides over and is carried by the reduceddiameter portion 138 of the operating stem 126 is journaled for slidingmovement in the bore 168. The inner end of the operating stern 126engages the adjacent surface of the disk 15S and holds this disk againstthe abutment 154. The sleeve 170 is in turn held in position on theoperating stern 126 by means of a nut 172 threaded thereon and whichholds a washer 174 against the outer end of the sleeve 170. A helicalcoil compression spring 176 is arranged concentrically about the sleeve17% externally of the plug 162 intermediate the adjacent end wall of theplug and the washer 174 and exerts a force urging the operating stern126 into the position shown in Fig. 3 in which the disk 158 engages theseat 120 and the disk 152 engages the seat 122.

The plug 164 is similar to the plug 162 and includes passageways 166aand bore 168:: in which is journaled a hollow cylindrical sleeve 178which fits on and is carried by the reduced diameter portion 140 of theoperating stem 126. The sleeve 178 holds the disk 170 in proper positionagainst the backing member 156. The sleeve 178 is held in position bymeans of a nutlike member 188 threaded on the end of the operating stem126 and holding a washer 182 against the sleeve 178. The nutlike memberis provided with a through aperture 184 which aligns with an aperture192 of an operating stem 186 of a solenoid actuator not illustrated inFig. 3 but identified as 70 in Fig. 6. A pin or other suitableconnecting means 190 (see Fig. 6) extends through apertures 184 and 192to connect the actuator 78 to member 180.

Upon energization of the actuator 70, the stem 126 will be withdrawninwardly toward the actuator moving the valve members 146 and 148 towardthe left away from the ports 120 and 122 and into engagement with theports 118 and 124. In this position of the valve device 44 the conduit42 is connected through the port 114 to a casing port 194 openingoutwardly through the casing 100 from the passageway 102 intermediatethe ports 122 and 124. This port 194 is connected to the conduit 46 sothat with the solenoid energized, the conduits 42 and 46 are connectedtogether for permitting the compressor 22 to withdraw refrigerant fromthe condenser 16. At the same time the disk 50 will engage the seat 118closing flow through the port 110 which normally connects the conduit 42with a casing port 196 and the conduit 48 which is connected to thedischarge port of the compressor 22 and placing the discharge conduit 48in open communication with the interior 50 of the housing 52 through theport 112 and the'passageway 166.

Upon de-energization of the actuator 70 spring 176 returns the valvedevice 44 to its normal position as shown in Fig. 3 in which the ports112 and 114 are closed whereby the conduit 48 is'in open communicationwith the conduit 42 through the port 110, and the conduit 46 is in opencommunication through the port 116 and passageway 166awith theinterior-50 of the housing 52. The system is now in normal coolingcondition in which the compressor is operable to draw vaporousrefrigerant from the evaporator '8 through conduit 54, the interior 50of the housing 52, the passageway 166a, port 116 and conduit 46 anddischarging this vaporous refrigerant under pressure'through the conduit48 into the conduit 42 to the condenser 16.

It will be noted'that there is a slight difference in area between thatdefined by the interior diameter of the seat- 122 and that defined bythe external diameter of the seat 120. Pressure within the space betweenthe seats 122 and 120, with the valve in the position of Fig.3, willtherefore urge the valves into engagement with their seats. Since theusual operating differential across the seats may be in thegeneral'magnitude of upwards oflOO pounds per square inch, a substantialclosing pressure acts to hold the valve in its set position. During thetime switch SW1 is open, the compressor or pump 22 will stop operatingand the pressures within the sealed refrigerating system will equalizethrough the tube 38.

With the pressures balanced, the force due to fluid pressure biasingthis valve to this position will, of course, disappear. When thepressure within the interior 50 of the housing 52 equalizes with thatwithin the conduits 42 and 48, only friction and the force of spring 176need be overcome by the solenoid actuator 70 to move the operatingstem126 to its actuated position in which the valve members 146 and 148engage the seats 118 and 124. Upon operation of the compressor 22 inthis position of thevalve, pressure will again build up in the conduit48'urging the valve member 146 tightly against the seat 118 and aid thesolenoid actuator 70 in maintaining the valve device 44 in its actuatedposition. Upon termination of the reverse cycle operation of the system,the switch SW1 again opens and'permits the pressure within theconduit'48 and interior 50 of the housing 52 to equalize with thatwithin the conduits 42 and 46 so that upon de-energization of theactuator 70, the spring 176 will move operating stem 126 into its normalposition.

In the modification shown in Fig. 4 the valve of Fig. 3 at is placedwithin a sealed housing 200 which may be located externally of thehousing 52 of the motor compressor unit 14. This construction isparticularly advantageous where there is insufficient room within thehousing 52 for the valve structure or to add such 'a structure toexisting motor compressor units which have been fabricated without thevalve device 44. In this construction the suction line 54 from theevaporator 8 opens into the interior of the housing 200. 'The port 196is connected by means of conduit 202'to the conduit 48 which normally isbrought out of the housing 52. The port 194 is connected by means of aconduit 204 'to the interior of the housing 52. In other respects theoperation and construction is similar to that shown in the form of Fig.2.

In Fig. 6 there is shown a modified form of valve device 44a which maybe used in place of the device 44 and in which like parts are indicatedwith like reference' characters to the device 44 shown in Fig. 3. Inthis form, however, the plug or end members 162a and 164a are notprovided with the passageways 166 or -166asince fluid flow through theend members 162a all.)

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minate inwardly of the ends of the sleeves 170a and 178a which sleevesare interiorly screw threaded for reception in the end portion ofthe'valve actuator 126a. The sleeves 170a and 178a are provided withspaced ports 300 and 302 which extend through side walls in thesesleeves and alternately communicatively connect the interior of thevalve housing 100 to the interior 50 of the casing 52. In the positionshown in Fig. 6, which is the normal refrigerating position, the port300 communicatively connects the port 194 with the interior of thehousing 52 and ports 102 and 196 are connected together. With the valveoperating stern 12611 in its other or reversed cycle position, the port300 of the sleeve 170a acts to communicatively connect the port 196 withthe interior of the housing 52 and to connect port 194 with port 192.The valve members 146a and 148a are similar to the valve members 146 and148 except they are provided with beveled seat engaging surfaces toengage the beveled valve ports 118a, 120a, 122a and 124a. It will beapparent that the valve members could be of metal and have ground seatengaging surfaces if desired.

During normal refrigerating operation of the refrigerating system ofFig. 2, the cam disk 62 will be engaging the disk follower 66 of theswitch SW1 to maintain switch SW1 in closed position whereby theenergization of the motor compressor unit 14 will be under control ofthe thermostatic 'control switch 34. The motor will be periodicallyenergized and de-energized to drive the compressor-22 for withdrawingvaporous refrigerant from the evaporator 8 and discharging this vaporousrefrigerant at high pressure into the condenser 16 in a normal manner toremove heat from the evaporator. The clock mechanism 18 is energizedconcurrently with the motor 20 to rotate the cam disk 62 which acts toadd up the running time of the motor 20. After sufiicient running timeof the motor compressor unit has occurred in which an appreciativeamount of frost may be expected to accumulate on the evaporator 8,the'cam disk 62 will have been rotated to the position shown in Fig. 7in which the cam disk follower 66 of the switch SW1 will havemoved intothe depression 84 opening the switch SW1 which breaks the circuit in theline 26 and prevents any running of the motor 20 to permit the pressuresin the refrigerating system to equalize. After a predetermined timeintervalsuflicient for'this purpose, the disk 62 will have rotatedsufficiently to cause the follower 86 of the switch SW2 to be raised bythe enlargement 88 to close the switch SW2. Ashort time later the disk62 will rotate sufficiently to cause the disk follower 66 to be raisedby theenlargement 91 sufiiciently to close the switch SW1.' Closure ofthe switch SW2 acts to energize. the solenoid actuator 70 for shiftingthe valve device 44 to close the ports 110 and 116 and open the ports112 and 114 and the subsequent closure of switch SW1 starts the motor20after the valve device 44 has been shifted. The switch SW1 ismaintained open due to the depressions 84 and 90 for a period sufficientto" permit the pressures within the refrigerating system tosubstantially equalize whereby there are no refrigerant pressure forcesacting to prevent movement. of the stem 126 of the valve device 44.

It will be apparent that, with the circuit as disclosed in Fig. 2, thedefrosting process of Fig. 2 is accomplished during an interval in whichthe temperature switch 34 is unsatisfied and is in the closed positionfor permitting operation of the motor 20 in which condition the motor 60will be energized and drive the timing cam 62. Upon reclosure of theswitch SW1 and energization of the motor 20 the pump 22 withdrawsvaporous refrigerant from the condenser 16 and discharges it into theinterior of the housing 52 from whence it flows through the conduit 54into the evaporator 8. This vapor will then condense within theevaporator 8 imparting its heat thereto to melt the frost which hasaccumulated upon the ti evaporator 3. Liquid refrigerant from theevaporator 8 flows through the small bore tube 38 into the condenser 16where it is evaporated tliereby absorbing heat from the condenser 16.This heat-laden vapor may again be withdrawn from the condenser 16 anddischarged back to the evaporator 8 through the conduit 54 by the pump22. At the end of a predetermined defrost time, the cam disk 64 willhave been rotated sufficiently in a clockwise direction to permit thedisk follower 66 to move into the depression 99 opening the switch SW1and terminating operation of the pump 22. At some time thereafter, thedisk follower 86 of the switch SW2 will pass from the enlarged camportion 88 down to the normal diameter portion opening the switch SW2 todeenergize the solenoid actuator 70. As soon as the pressures within thesystem equalize which occurs as above set forth due to the opencapillary tube 38, the spring 176 of the valve device 44 will move theoperating stem 126 back to its shown position in Fig. 3. The length oftime that the switch SW1 is held in open position by depression 90 ofthe cam 62 is sufficient to accomplish this equalization of pressures.After this predetermined time, the disk 62 will rotate still further inthe clockwise direction lifting the disk follower 66 back to the normaldiameter portion 68 of the cam 62 again reclosing the switch SW1 fornormal refrigerating operation of the system under control of the switch34.

The operation of the system shown in Fig. 5 is substantially the same asthat shown in Fig. 2 except that the clock 18 is continually energized,it being supplied with energy from the lines L1 and L2 on the sourceside of the thermostatic switch 34. Therefore the defrosting operationin this system will occur periodically rather than as a function ofcompressor operating time. The switch SW3 is operated along with theswitch SW2 to complete a circuit in parallel with the thermostaticswitch 34 so that solenoid 70 and the motor 22 may be energizedirrespective of the operating condition of the thermostatic switch 34.By the use of the particular type of valve structure and the particulartiming mechanism, it is possible to provide a valve device which may beoperated by a solenoid of minimum size and may be placed within theinterior of most of the standard sealed motor compressor units now foundon the market. The solenoid is not called upon to actuate the valve whenthere is any pressure differential acting to maintain the valve membersagainst their respective valve seats and also during the running of theunit 14 the valves are held closed by the pressure difference maintainedby the pump 22 In the preferred form of the invention the valve 44 or44a is placed within the housing 52 of the motor compressor unit 14. Inits more generic form the valve 44 or 44a is placed somewhere within thesealed refrigeration system. Furthermore, the invention contemplatessuch a unit which need not be provided with sealing means which wouldboth be expensive and tend to increase the power required to actuate thevalve device. Also, the invention contemplates a system in which minimumpower is required to rearrange the system elements, and the apparatusfor accomplishing the same is economical of construction and operationand requires a minimum of space.

What is claimed and is desired to be secured by United States LettersPatent is as follows:

1. In a domestic electric refrigerator, a refrigeration fluid systemcomprising an evaporator, a condenser, a compressor and a valvemechanism, means for driving said compressor, said valve mechanism beingoperable to connect said compressor to pump fluid from said evaporatorto said condenser when in a first position and when in a second positionto connect said compressor to pump fluid from said condenser to saidevaporator, actuator means for moving said valve mechanism between saidpositions, a pair of control means one of said control means regulatingthe driving of said comiii pressor by said driving means and the otherof said con-- trol means regulating the operation of said valvemechanism moving means, and means operating said pair of control meansand effective to actuate said one control means to render saidcompressor driving means ineffective to drive said compressor and tomaintain said other control means effective to actuate said valve movingmeans so that said valve mechanism can be actuated to one of its saidpositions during periods in which said compressor driving means isineffective to drive said compressor, said last-named means thereafteractuating said one control means to drive said compressor andmaintaining said other control means effective to maintain said valvemoving means actuated.

2. The combination of claim 1 in which an unloader means is provided tobalance the pressures across said valve mechanism during periods inwhich said compressor driving means is ineffective to drive saidcompressor and in which said one control means acts to maintain saidcompressor driving means ineffective for a suflicient time period topermit said pressures to balance.

3. The combination of claim 2 in which said unloader means comprises asmall bore tube connecting said condenser to said evaporator.

4. The method of operating a refrigerating system having a compressor,evaporator, condenser, a reversing valve for controlling flow ofrefrigerant between the compressor and the evaporator and the condenser,and means for equalizing the refrigerant pressures across said valvewhich method comprises the steps of maintaining said valve in a normalposition for permitting said compressor to withdraw refrigerant fromsaid evaporator and to discharge the withdrawn refrigerant into saidcondenser, of operating said compressor with said valve in said normalposition to cool said evaporator, of discontinuing said compressoroperation for a time interval sufficient to permit said equalizing meansto equalize the pressures across said reversing valve, of reversing saidreversing valve to reverse the direction of fiuid flow whereby said flowis from said compressor to said evaporator, said reversing of said valveoccurring during the period in which compressor operation isdiscontinued, of thereafter operating said compressor with said valve inits reversed position for a predetermined time interval for the purposeof defrosting the evaporator, and of thereafter returning said reversingvalve to its said normal position.

5. The method of claim 4 in which the said reversing valve is returnedto its normal position during a time period in which said compressor isineffective and the pressures across said valve means are substantiallyequalized.

6. In a refrigerating system, an evaporator, a condenser, a motor, acompressor having an input and an output connected to be driven by saidmotor, a housing enclosing said compressor and said motor, a first smallbore conduit connecting said evaporator to said condenser, a secondconduit connecting said evaporator to said housing, a valve body withinsaid housing, a third conduit connecting said compressor output to saidbody, a fourth conduit connecting said compressor inlet to said valvebody, a fifth conduit connecting said body to said condenser, said bodyhaving a fluid flow means opening into said housing, fluid flowdirecting means operable in one position to direct fluid flow from saidfluid flow means to said fourth conduit and from said third conduit tosaid fifth conduit and operable in a second position to direct fluidflow from said third conduit to said fluid flow means and from saidfifth conduit to said fourth conduit.

7. In a refrigerating system, an evaporator, a condenser, a motor, acompressor having an input and an output connected to said motor, amotor-compressor housing enclosing said compressor and said motor, afirst small bore conduit connecting said evaporator to said'condenser, asecond conduit connecting said evaporator to said motor-compressorhousing, a valve device having a body within said motor-compressorhousing, said body comprising an elongated valve housing having acentral passageway extending therethrough and opening outwardly throughopposite end portions of said valve housing, said valve housinghavingoppositely facing valve seats in said passageway facing said endportions, plug members carried by said end portions and overlying saidpassageway openings, said plug members being provided with valve seatsfacing said first-named seats, said plug members having aperturesextending therethrough and opening into said passageway through saidplug seats, a valve stemwithin said passageway, a pair of valve memberseach having oppositely facing seat engaging surfaces carried by saidstem, one of said valve members being located intermediate one of saidfirst-named seats and one of said plug member seats, the other of saidvalve members being located intermediate the other of said first-namedseats and the other of said plug membet seats, the relative spacingbetween said valve members and said seats being such that when said stemis in a first position said one valve member engages said onefirst-named seat said other valve member engages said other plug memberseat and when said stem is in a second position said other valve memberengages said other first-named seat said one valve member engages saidone plug member seat, and tubular members carried by said stem andjournaled within said plug member apertures, said valve housing having afirst port opening into said passageway intermediate said first pair ofseats and a second port opening into said passageway intermediate saidone housing seat and said one plug member seat and a'third port openinginto said passageway intermediate said other housing seat and said otherplug member seat, a third conduit connecting said compressor output tosaid second port, a fourth conduit connecting said compressor inlet tosaid third port and a fifth conduit connecting said body to said firstport.

8. The combination of claim 7 in which there is provided a timing meansactuated as a consequence of the energization of said motor to controlthe position of said stem.

9. The combination of claim 8 in which said timing means'acts tode-energize said motor for a desired time interval to permit movement ofsaid stem from said second to said first position, re-energize saidmotor for a desired interval to permit fluid to be pumped into saidevaporator, and to de-energize said motor for a desired time interval topermit movement of said stem from said first position to said secondposition.

10. In a refrigerating apparatus, a compressor, an evaporating element,a condensing element, an expansion device, means connecting saidcompressor, said device and said elements together into a closedrefrigerating system whereby hcat laden refrigerant is transferred bysaid compressor from one of said elements to the other of said elementsand said expansion device permits flow of refrigerant'from said otherelement to said one element, a reversing valve connected into andforming a part of said system and having a normal operating position inwhich said compressor is connected to transfer refri erant from saidevaporating element to said condensing element and having a defrostingposition in which said compressor is connected to transfer refrigerantfrom said condensing element to said evaporating element, a sequencingdevice having a pair of actuators for actuating a valve controller and acompressor controller in sequence, means including said valve controllerfor controlling the positioning of said reversing valve, means includingsaid compressor controller for rendering said after actuate said valvecontroller to move said reversing valve from its said normal position toits said defrosting position, to thereafter actuate said compressorcontroller to render said compressor effective, to thereafter actuatesaid compressor controller to render said compressor ineffective, tothereafter actuate said valve controller to move said reversingvalvefrom its said defrosting position to its said normal position, and tothereafter actuate said compressor controller to render said compressoreffective.

11. The combination of claim 10 in which said sequencing device isoperated as a function of time and in which said expansion device is anormally open flow restricting device \vhereby during periods in whichsaid compressor is ineffective said expansion device is effective toequalize the pressures between said elements.

12. In a refrigerating apparatus, an evaporator having a pair of ports,a condenser having a pair of ports, a compressor having an inlet and anoutlet, an expansion device connected between one of said ports of saidcondenser and one of said ports of said evaporator, 21 normal controlfor controlling the operation of said compressor, a non-balanced typereversing valve having a normal position and a reversing position, meansincluding said reversing valve for connecting said evaporator and saidcondenser and said compressor together into a closed system, said valvewhen in said normal position connectingthe other of said ports of saidevaporator to said compressor inlet and connecting the other of saidports of said condenser to said compressor outlet whereby saidcompressor causes refrigerant to flow from said evaporator to saidcondenser, said valve when in said reversing position acting to reversethe refrigerant flow whereby said compressor causes refrigerant to flowfrom said condenser to said evaporator, positioning means foractuatingsaid valve between its said positions, a controller for regulating theoperation of said compressor, and a timer having a time'actuated elementfor controlling said controller and effective to actuate said controllerinto a first position to stop operation of said compressor and tothereafter actuate said positioning means to cause said reversing valveto move from its said normal position to its said reversing position, tothereafter actuate saidcontroller to start operation of said compressorwhereby said compressor becomes effective to transfer refrigerant, tothereafter actuate said controller to stop operation of said compressor,to thereafter actuate said positioning means to cause said reversingvalve to move to its said normal position, and to thereafter actuatesaid controller to render said compressor responsive to said normalcontrol.

13. In a domestic electric refrigerator, a refrigeration fluid systemcomprising an evaporator, a condenser, a compressor, valve mechanism andmeans for equalizing the pressure between said condenser and saidevaporator during periods in which said compressor is not being driven,means for driving said compressor, said valve mechanism having a normalrefrigerating position in which it connects said compressor to pumpfluid from said evaporator to said condenser and having an evaporatordefrosting position in which it connects said compressor to pump fluidfrom said condenser to said evaporator, a force exerting actuator forexerting a force to urge said valve to its said defrosting position, acompressor control device for rendering said compressor driving meanseffective and ineffective to drive said compressor, a valve controldevice for'actuating said valve actuator whereby said actuator iseffective to exert a force in a direction to move said valve from saidnormal position to said defrosting position, means actuating saidcontrol devices to provide for operation of said control devices in adesired sequence, said sequence including a first interval in which saidcompressor control device maintains driving means ineffective to drivesaid compressor and maintains said valve control device effective toexert its said force for urging said valve mechanism to saiddefrostingposition whereby said valve mechanism will move to saildefrosting position during the time said driving means is ineffective todrive said compressor, said sequence further including a second intervalfollowing said first interval in which said valve control device isineffective to urge said valve mechanisms to said normal position andsaid compressor control device is actuated to establish operation ofsaid compressor.

14. In a domestic electric refrigerator, a refrigeration fluid systemcomprising an evaporator, a condenser, a compressor, valve mechanism andmeans for equalizing the pressure between said condenser and saidevaporator during periods in which said compressor is not being driven,means for driving said compressor, said valve mechanism having a normalrefrigerating position in which it connects said compressor to pumpfluid from said evaporator to said condenser and having an evaporatordefrosting position which it connects said compressor to pump fluid fromsaid condenser to said evaporator, an actuator for urging said valvebetween its said positions, said valve mechanism including elementsresponsive to the differential in pressure between said evaporator andsaid condenser, said elements being eifective to prevent movement ofsaid valve by said valve actuator when the pressure differential betweensaid evaporator and said condenser is above a predetermined magnitude, acompressor control device for rendering said compressor driving meanseffective and ineffective to drive said compressor, a valve controldevice for actuating said valve actuator whereby said valve is urged ina direction to move from said normal position to said defrostingposition, means actuating said control devices to provide for operationof said control devices in a desired sequence, said sequence including afirst interval in which said compressor control device maintains saidcompressor ineffective to establish said predetermined magnitude ofpressure difference and said valve control device is maintainedeffective to urge said valve mechanism to said defrosting positionwhereby said valve mechanism moves to said defrosting position during aperiod in which said pressure difierence is below said predeterminedmagnitude, said sequence further including a second interval followingsaid first interval in which said valve control device continues to beefiective to urge said valve mechanisms to said defrosting position andsaid compressor control device is actuated to establish operation ofsaid compressor.

15. The method of defrosting an evaporative type refrigerating systemhaving an evaporator portion, a condenser portion, a fluid pump, conduitmeans connecting said portions and said pump into a closed system inwhich said pump transfers fluid between said portions, a reversing valvein said system for selecting the one of said portions to which said pumpdelivers fluid, and an automatic element for controlling the operatingperiods of said fluid pump, said method comprising the steps ofinterrupting the operation of the pump during a time interval in whichthe automatic element is attempting to maintain the pump operating, ofmaintaining said interruption for a time interval sufficient to permitan equalization of pressures across the reversing valve,

of shifting the valve during the period of equalized pressures, ofthereafter returning the control of the fluid pump to the automaticelement for a predetermined defrosting time interval in which heatextracted from the condenser is supplied to the evaporator fordefrosting the evaporator, and of thereafter shifting the valve to itsnormal position to permit the fluid pump to remove heat from theevaporator to the condenser under control of the automatic element.

16. The method of claim 15 which includes the subsequent steps ofinterrupting the operation of the pump at the end of said defrostinginterval for a time interval suflicient to permit an equalization ofpressure across the reversing valve prior to the shifting of the valveto its normal position, and the step of returning the control of thepump to the automatic element subsequent to the step of returning thevalve to its normal position.

References Cited in the file of this patent UNITED STATES PATENTS1,619,196 Davenport Mar. 1, 1927 2,324,309 McCloy July 13, 19432,342,174 Wolfert Feb. 22, 1944 2,351,140 McCloy June 13, 1944 2,375,157Wilkes et a1. May 1, 1945 2,381,651 Dickens Aug. 7, 1945 2,395,941Rockwell Mar. 5, 1946 2,433,574 Newton Dec. 30, 1947 2,446,910 DickensAug. 10, 1948 2,509,099 Jones May 23, 1950 2,548,324 Smith Apr. 10, 19512,556,104 Ransdell et a1 June 6, 1951

